John, I had a similar problems with Acurus amps (A250 and a 200x3)... it's a ground problem. I managed to solve it by running ground lines from every component to the screw in the outlet the components were plugged into... It seems the cable wire is truly a definitive ground, so the cable folks tell me, so by bettering the rest of your systems ground you should be OK.
Good luck!
Good luck!